public class Problem15 {
	public static void main(String[] args) {
		int size = Integer.parseInt(args[0]);
		long[][] map = new long[size][size];

		map[0][0] = 1;

		for (int i = 1; i < map.length; i++)
			map[i][0] = 1L;
		
		for (int j = 1; j < map[0].length; ++j)
			map[0][j] = 1L;
	
		for (int i = 1; i < map.length; ++i) {
			for (int j = 1; j < map[0].length; ++j) {
				map[i][j] = map[i-1][j] + map[i][j-1];
			}
		}

		System.out.println("" + map[size-1][size-1]);
	}
}
